1. Field of the Invention
The present invention relates to an intersection driving support apparatus that informs a driver driving a vehicle attempting to enter a priority road from a non-priority road of support information concerning moving objects on the priority road.
2. Description of Related Art
In the related art, generally at an intersection that is not signalized, a traffic sign of “STOP” is put up and a stop line is drawn on the surface of a non-priority road that intersects with a priority road. When a priority road has two lanes, the center line thereof may be drawn without being interrupted on an extension of a non-priority road. Thus, a driver attempting to advance his/her vehicle into a priority road from a non-priority road recognizes that the road on which the vehicle is currently traveling is a non-priority road by visually observing the traffic sign, the stop line or the center line. Then, the driver slows down before the intersection, stops at the stop line and advances into the priority road while making sure that it is safe to advance.
In this case, when a blocking object such as a building is present around the intersection, a driver of a sedan type vehicle or a wagon type vehicle, which has an engine in a front portion of a vehicle body, cannot readily recognize a bicycle or a vehicle traveling on the priority road due to the blocking object even if he/she stops his/her vehicle at a position where a front bumper thereof is over the stop line, because the front end of the vehicle body is far from the driver seat. When the driver attempts to enter a priority road through such a blind intersection, the driver advances at reduced speed so that the front end of his/her vehicle enters the priority road to ensure good visibility and grasps the conditions of the priority road to make sure that it is safe to advance, and then makes his/her vehicle merge onto the priority road.
However, if a vehicle traveling on the priority road is about to pass through the intersection when the driver attempts to advance the front end of his/her vehicle into the priority road, it is likely that the vehicles crash into each other as they enter the intersection. Therefore, in order to prevent such an intersection collision, there have been proposed various driving support apparatuses designed to support a driver by informing the driver attempting to advance his/her vehicle into a priority road of information on the priority road so that the vehicle can advance safely.
For example, Japanese Patent Unexamined Application Publication (JP-A) No. 2006-185137 (hereinafter referred to as Patent Document 1) discloses a technique for calculating the times at which a subject traveling on a non-priority road vehicle and an oncoming vehicle traveling on a priority road arrive at an intersection by means of inter-vehicle communication between the subject vehicle and the oncoming vehicle, and setting an informing timing and an alarming level of support information such as a crash alert according to a traveling condition of the oncoming vehicle at the time when the subject vehicle enters the intersection.
The technique disclosed in Patent Document 1 is disadvantageous in that the driver may feel troublesome because, when for example, entering a priority road from a non-priority road, the driver is informed of every support information as a vehicle traveling on the priority road approaches even if the driver has good visibility of the priority road and can readily grasp the conditions of the priority road by visual observation.
In addition, even if the vehicle traveling on the priority road turned right or left before the intersection and thus the danger of crash with the subject vehicle has disappeared, the alerting support information is continuously informed until the two vehicles are away from each other to by certain distance. In such case, the driver attempting to enter the priority road from the non-priority road believes that a vehicle traveling on the priority road approaches, and therefore he/she may disadvantageously recognize the support information as false information due to the fact that the vehicle does not appear.